The microscopical pattern of growth of Mycobacterium leprae-murium "Douglas" in microcolonies

A thin section technique of Ogawa egg yolk culture medium inoculated with Mycobacterium leprae-murium was found to reveal microscopical growth of the strain which could not be demonstrated by macroscopical examination. A peculiar structure of the growth, characterized by many lytic spots different in size, was observed indicating the possible presence of a temperate phage which may interfere with the synthesis of nucleic acids needed for the active multiplication of M. leprae-murium.